A post on Halo Waypoint stated that week 2 for Halo 5: Guardians Beta will see a new game type and new maps.
The new game type is Breakout, which is round-based and you only have one life each round. The first team to take five rounds wins the match. Two news maps will be added that you can play on, Crossfire and its variant, Trench.
Along with all of that, two new maps will be swapped into the Slayer playlist, Regret and Eden.
Regret is a remix of Truth, and Eden is a remix of Empire, both of which were included in week 1. Additionally, you voted, and we answered: You’ll be able to wield the Hydra MLRS, a brand-new weapon to the Halo universe, while slaying on Regret. – Halo Waypoint